u/Careful-Falcon-36

ERR_REQUIRE_ESM is still my villain in 2026 Third project this month where someone added chalk v5 or node-fetch v3 and suddenly half the codebase breaks. The thing that took me too long to internalize: its not symmetric. ESM can pull from CJS just fine, but CJS hard-blocks on ESM its not a config issue, it's by design because of how the loaders work. Also burned by the __dirname thing more times than I'd like to admit. And the dual-package hazard is completely silent no error, just two instances of the same module running and your singleton state going nowhere. Documented everything I kept hitting. Link in comments if anyone wants it.

I was working on a Node.js API that was extremely slow — it took around 15-18 minutes to fetch 8,000 records.

The issue wasn’t Node.js itself, but how MongoDB queries and aggregations were written.

Here’s what I found and fixed:

• Missing indexes on frequently queried fields
• Heavy aggregation pipelines without optimization
• Fetching unnecessary data (no projection)
• Inefficient query structure

After optimizing indexes and rewriting aggregations, the response time dropped to 15-25 seconds.

I wrote a detailed breakdown with examples here: https://www.stackdevlife.com/blog/nodejs-mongodb-api-performance-optimization

Would love to know how others handle large dataset performance in Node.js APIs.

When I started working with Next.js, I made mistakes by using NEXT_PUBLIC_ for sensitive keys and overlooked it many times. Later, during a code review, I realized that such keys should not be exposed publicly.

That’s why I wrote about what’s actually leaking in Next.js — and how to stop it.

If you have any better suggestions, please let me know.

The fix wasn't complicated but it changed how I think about external data.

How are you handling API response types in your projects?